Serial wafer handling mechanism

ABSTRACT

A wafer handling system for a wafer processing apparatus includes a wafer load lock chamber, a wafer processing chamber and a transfer chamber operatively coupled to the wafer load lock chamber and the wafer processing chamber. The transfer chamber includes a wafer transfer mechanism comprising a transfer arm pivotably coupled to a portion of the transfer chamber which forms an axis. The transfer arm is operable to rotate about the axis to transfer a wafer between the wafer load lock chamber and the process chamber in a single axis wafer movement. The invention also includes a method of transferring a wafer to a wafer processing apparatus. The method includes loading a wafer into a wafer load lock chamber and rotating a transfer arm into the wafer load lock chamber to retrieve the wafer therein. The method further includes rotating the transfer arm out of the wafer load lock chamber and into a process chamber to deposit the wafer therein, wherein the rotating of the transfer arm occurs in a single axis wafer movement.

FIELD OF THE INVENTION

[0001] The present invention relates generally to semiconductorprocessing systems, and more specifically to a system and method fortransferring a wafer or other planar type substrate to a processingapparatus.

BACKGROUND OF THE INVENTION

[0002] The fabrication of integrated circuits and other type devicestypically employs a series of fabrication steps in which a semiconductorwafer or other type substrate is processed within various processingsystems. For example, a semiconductor wafer is subjected to photoresistand other film depositions and patterning steps, implantation anddiffusion type processing, etc. The diverse processing steps areexecuted in a variety of different processing systems, for example,photoresist ashing systems, dry etch systems, ion implantation systems,chemical vapor deposition systems, etc. For each of the above processingsystems, control of contamination is imperative for a cost-effective,reliable manufacture of such devices. Furthermore, because design rulesfor integrated circuits require ever-decreasing critical dimensionfeature sizes, it is necessary to provide improved control overparticulate contamination within such systems.

[0003] Some of the primary sources of particulate contamination inintegrated circuit processing are personnel, equipment and chemicals.Particulates generated or “given-off” by personnel are transmittedthrough the processing environment and may result undesirably in devicedefects. Particulates within the equipment and chemicals associatedtherewith are often called process defects and are caused by frictionalcontact between surfaces in the equipment and impurities within thesupply gases or chemicals. One significant source of such processdefects is contamination associated with the storage transportation ofwafers from one processing system to another.

[0004] Various mechanisms have been developed to isolate the wafer fromparticles during the storage, transport and processing of wafers in theprocessing equipment. For example, the Standard Mechanical Interface(SMIF) system has been created to reduce particle contaminations.

[0005] In a typical SMIF system, a box or carrier is placed at theinterface port of the processing apparatus; latches release the box doorand port door simultaneously. The doors on the carrier mate with thedoors on the interface port of the processing equipments and opensimultaneously so that particles which may have been on the externaldoor surfaces are trapped between the doors and thus do not contaminatethe processing chamber.

[0006] Regardless of the various attempts made to minimize processdefects, contamination problems still persist. Another method ofreducing process defects associated with such contamination is byconstantly evacuating and re-pressurizing the process chamber as wafersare transferred thereto and therefrom. A method for effectuating suchcontamination reduction is illustrated in prior art FIG. 1 anddesignated generally at reference numeral 10. Typically, a multi-wafercassette is located local to the processing chamber at ambientatmosphere, while a wafer within the process chamber is processed at asubstantially reduced pressure, for example, about 1 millitorr at step12. After the processing is complete, the wafer is removed at step 14 byopening the process chamber to allow transfer of the processed waferback into the multi-wafer cassette.

[0007] Subsequent to the wafer removal, the process chamber is pumpeddown to a pressure significantly lower than the processing pressure, forexample, about 1 microtorr at step 106 in order remove any contaminationthat may have been introduced by opening the chamber door. A load lockvalve is then opened and a new wafer is then loaded into the processchamber at step 18. The load lock valve is then closed and the chamberis again pressurized to the desired process pressure at step 20.Although the above method 10 generally is effective at minimizingcontamination to a reasonable level, the method 10 involves “pump andvent” cycles between the loading of each wafer into the chamber whichnegatively impacts processing throughput. As is well known to thoseskilled in the art, because processing equipment is a significantcapital expenditure, low equipment throughput is highly undesirable.

[0008] Another problem associated with certain types of semiconductorprocessing equipment is related to the doorway or access port into theprocess chamber. Typically a wafer transfer endstation mates with arectangular or box-like doorway or access port of the process chamber.The process chamber isolates the internal portion of the chamber fromthe outside environment during processing by actuating a slot valveassociated with the access port. The slot valve-access port interface,however, results in an asymmetry within the process chamber which insome processes, for example, plasma immersion ion implantation, mayresult in temperature variation, plasma density non-uniformity and othertype non-uniformities within the process. Such non-uniformities maynegatively impact process control and the like.

[0009] There is a need in the art for a semiconductor processing systemand method which minimizes process chamber contamination, increaseswafer throughput and improves semiconductor process control.

SUMMARY OF THE INVENTION

[0010] The present invention is directed to a wafer processing systemwhich efficiently handles the transfer of wafers to and from a waferprocessing chamber in a manner which reduces chamber contamination,increases wafer throughput and improves process control.

[0011] According to one aspect of the present invention, a waferprocessing system and associated method is disclosed which efficientlyhandles the transfer of a wafer to and from a wafer processing chamberwithout requiring an evacuation of the processing chamber for each wafertransfer. The system includes a load lock chamber, a process chamber anda transfer chamber therebetween. A portion of the load lock chamber issealed or otherwise isolated from the transfer chamber and the processchamber when a wafer is transferred thereto. The load lock chamberportion is then evacuated or otherwise pumped to substantially equalizethe pressure between the load lock chamber portion and the remainingportion of the load lock chamber, transfer chamber and process chamber.Upon pressure equalization, the load lock chamber portion containing thewafer is brought into fluid communication with the transfer chamber andthe process chamber, and the wafer is transferred to the processingchamber via the transfer chamber. According to the present invention,the use of one or more such load lock chambers allows transfer of wafersto the process chamber without the need for an evacuation thereof,thereby minimizing process chamber contamination and increasing waferthroughput.

[0012] According to another aspect of the present invention, a ringvalve and associated method is disclosed. The ring valve resides withinor is otherwise associated with the process chamber and is operable tomove between an open and closed position therein to selectively seal theprocess chamber from the remainder of the wafer processing system. Inthe open ring valve position, the interior of the processing chamberforms a top chamber portion and a bottom chamber portion defining anannular spacing therebetween. In the open position, the ring valveexposes a process chamber access port at a portion of the annularspacing through which the transfer chamber is coupled and the processchamber is accessed. In the closed position, the ring valve couples thetop and bottom interior chamber portions together, thereby sealing theprocessing chamber from the transfer chamber and load lock chamber,respectively. In addition, the ring valve has a substantially uniforminterior peripheral surface which provides a peripheral uniformitywithin the processing chamber, thereby facilitating uniform processingconditions therein.

[0013] According to yet another aspect of the present invention, asingle axis wafer movement transfer arm and associated method of wafertransfer is disclosed. The transfer arm avoids the multi-axis,multi-jointed articulated robotic arms of prior art systems, therebyreducing the particle generation and contamination associated therewith.The transfer arm includes an elongate member which is rotatably coupledto a portion of the transfer chamber about an axis which permitsrotational movement of the transfer arm between the load lock chamberand the process chamber. Preferably, the arm is rotatably coupled to thetransfer chamber at a midpoint thereof and contains end effectors ateach end for simultaneous wafer transfer between the process chamber andthe load lock chamber in an efficient manner.

[0014] Preferably, the transfer arm of the present invention is utilizedin conjunction with a dual load lock chamber processing systemarrangement. In such case, two such transfer arms are implemented androtate about separate axes to and from the process chamber from separateload lock chambers. That is, one transfer arm rotates about a first axiswhile the other transfer arm rotates about a second axis. In the abovemanner, one load lock chamber may be loaded externally with a wafer andundergo a pump and vent cycle while the other load lock chamber istransferring and receiving thereto wafers with the process chamber. Inthe above manner, wafers are transferred to and from the process chamberin an efficient manner without substantial contamination associatedtherewith, thereby improving process yield and throughput.

[0015] To the accomplishment of the foregoing and related ends, theinvention comprises the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrativeembodiments of the invention. These embodiments are indicative, however,of but a few of the various ways in which the principles of theinvention may be employed. Other objects, advantages and novel featuresof the invention will become apparent from the following detaileddescription of the invention when considered in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a flow chart diagram illustrating a prior art method oftransferring a wafer to a wafer processing chamber, wherein the processchamber undergoes a pump and vent cycle for each wafer transferredthereto;

[0017]FIG. 2 is a cross sectional view of an exemplary plasma immersionion implantation system;

[0018]FIG. 3 is a system level cross sectional view illustrating a ringvalve and multi-chamber processing system for eliminating processchamber pump and vent cycles according to the present invention;

[0019]FIG. 4a is an exploded, fragmentary cross sectional view of aportion of the process chamber of FIG. 3, wherein a ring valve isillustrated in an open, retracted position;

[0020]FIG. 4b is an exploded, fragmentary cross sectional view of aportion of the process chamber of FIG. 3, wherein a ring valve isillustrated in a closed position to seal the process chamber;

[0021]FIGS. 5 and 6 are perspective views illustrating a prior artmulti-axis, multi-jointed articulated robot arm in extended andretracted positions, respectively;

[0022]FIGS. 7a-7 d are top plan views illustrating a plurality ofpositions of the prior art robot arm of FIGS. 5 and 6 depictingextended, retracted and intermediate positions, respectively;

[0023]FIG. 8a is a top plan view of a wafer processing system employinga single axis wafer movement transfer arm in a transfer positionaccording to the present invention;

[0024]FIG. 8b is a top plan view of the wafer processing system of FIG.8a illustrating the single axis wafer movement transfer arm in a neutralposition according to the present invention;

[0025]FIGS. 9a-9 d are top plan views of a wafer processing systememploying a wafer transfer arm which traverses a generally ellipticalwafer transfer path in a number of different wafer transfer positionsaccording to the present invention;

[0026]FIG. 10a is a top plan view of a wafer processing system employingmultiple load lock chambers and two single axis wafer movement transferarms, one being in a transfer position and the other in a neutralposition according to the present invention;

[0027]FIG. 10b is a top plan view of the wafer processing system of FIG.10a illustrating the single axis wafer movement transfer arms of FIG.10a in different positions according to the present invention;

[0028]FIGS. 11a-11 d are top plan views of a wafer processing systemhaving two load lock chambers and employing two wafer transfer armswhich traverse generally elliptical wafer transfer paths in a number ofdifferent wafer transfer positions according to the present invention;

[0029]FIG. 12 is a flow chart diagram illustrating a methodology fortransferring wafers to and from a process chamber without a processchamber pump and vent cycle for each wafer transfer according to thepresent invention; and

[0030]FIGS. 13a-13 c are flow chart diagrams illustrating anothermethodology for transferring wafers to and from a process chamber viamultiple load lock chambers without a process chamber pump and ventcycle for each wafer transfer according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will now be described with reference to thedrawings wherein like reference numerals are used to refer to likeelements throughout. The present invention includes a wafer processchamber, wafer handling system and associated method which incorporatesseveral inventive features that improve the throughput of the waferprocessing system, reduce contamination associated with wafer handlingand transfer, and improve process control therein.

[0032] The present invention includes a ring valve in conjunction withthe process chamber. The ring valve extends peripherally throughout aportion of the process chamber and is operable to move between an openposition and a closed position, wherein in the open position an accessport is revealed or otherwise defined which allows a wafer to enter orexit the process chamber. In the closed position, the ring valveeffectively closes the access port and provides a substantially uniformsurface about an interior peripheral portion of the process chamber,thereby facilitating uniform processing conditions within the processchamber and improving process control.

[0033] In addition, the present invention provides for single axis wafermovement between a load lock chamber and a process chamber via anon-jointed wafer transfer arm. The transfer arm preferably includes anelongate transfer member which is rotationally coupled to an axis pointin a transfer chamber. The elongate transfer member includes endeffectors or other type wafer contact manipulators generally at eachdistal end thereof which rotate in a wafer transfer plane between aneutral position in the transfer chamber and wafer engagement positions(transfer positions) in the load lock chamber and process chamber totransfer wafers therebetween. Due to the single axis rotation, thenon-jointed transfer arm of the present invention reduces substantiallythe number of moving parts which frictionally engage one another, andthereby reduces particle contamination associated therewith, and allowsthe system to keep process gas in the transfer chamber at the samepressure as the process chamber.

[0034] Accordingly, the present invention further includes a load lockchamber and transfer chamber associated with the process chamber whichallows for selective fluid isolation between the load lock chamber andthe process chamber. Consequently, wafers may be transferred to theprocess chamber via the transfer arm without having to pump and vent theprocess chamber for each wafer transfer, thereby reducing contaminationassociated therewith and increasing system throughput.

[0035] The various features of the present invention will be describedbelow in conjunction with a plasma immersion ion implantation system asan exemplary embodiment. It should be understood, however, that thepresent invention may also be used in conjunction with other typesemiconductor or other type substrate processing systems (e.g.,photoresist ashing systems, dry etch systems, ion implantation systems,chemical vapor deposition systems, etc.) and such systems arecontemplated as falling within the scope of the present invention.

[0036] Referring now to the drawings, FIG. 2 discloses an exemplaryconventional plasma immersion ion implantation system, and is generallydesignated at reference numeral 100. The system 100 includes anevacuated process chamber 105 that is defined by an electricallyactivatable wafer support platen 110 mounted on an insulator 115, anelectrically grounded chamber housing 120 having walls 125 associatedtherewith, and a quartz window 130. Plasma which is generated within thechamber 105 contains ions of a desired dopant species (e.g., arsenic)that are implanted into a substrate, such as a semiconductor wafer Wlocated therein, when a negatively charged voltage is applied to theplaten 110. As shown in FIG. 2, the wafer W is lifted off of the platenby pins 135 operated by pin assemblies 140. In this manner the wafer maybe positioned vertically in a wafer transfer plane and installed intoand removed from the plasma chamber via an access port 145 and a loadlock assembly (not shown).

[0037] The plasma is generated in the process chamber 105 as follows. Anionizable dopant gas is introduced into the process chamber 105 by meansof an inlet 150 and a perforated annular channel 155 that resides aboutthe upper periphery of the chamber. A radio frequency (RF) generator 160generates an RF signal (on the order of 13.5 megahertz (MHz)) which iscoupled to a matching network 165. The matching network includescapacitors 170 that capacitively couple the RF signal to a generallyplanar antenna 175, having inner and outer circular coils, via leads 180and 185. Matching the impedance of the RF generator 160 with the loadimpedance insures maximum power out of the antenna 175 by minimizingreflection of the RF signal back into the generator. One such type ofmatching network 165 is known as an “inverted L” network, wherein thecapacitance of the capacitors 170 is varied by servomotors, dependingupon operating conditions.

[0038] The RF current generated within the antenna 175 creates amagnetic field that passes through the quartz window 130 into theprocess chamber 105. The magnetic field lines are oriented in thedirection shown by arrows B, based on the direction of current throughthe antenna coils. The magnetic field penetrating the process chamber105 through the quartz window 130 induces an electric field in theprocess chamber. This electric field accelerates electrons, which inturn ionize the dopant gas, which is introduced into the chamber throughthe annular channel 155, to create a plasma. The plasma includespositively charged ions of the desired dopant that are capable of beingimplanted into the wafer W when a suitable opposing voltage is appliedto the platen 110 by the modulator 190. Because the implantation processoccurs in a vacuum, the conventional process chamber 105 is evacuated bypumps (not shown) via the pump manifold 195.

[0039] Electromagnetic coils 196, 197, 198, and 199 are located outsideof the process chamber 105. The purpose of the coils is to vary themagnetic field within the process chamber 105 to vary the plasmadiffusion rate, which alters the radial distribution of plasma densityacross the surface of the wafer, to insure a uniform implant of ionsacross the surface of the wafer W. The electromagnetic coils of FIG. 2include two larger main coils 196 and 199 disposed above and below,respectively, and two smaller trim coils 197 and 198, which residecloser in proximity to the process chamber 105. In addition, the waferplaten 110 includes a dosimetry detector such as a plurality of Faradaycurrent collectors or cups 192 that are used to measure plasma currentdensity and thereby provide an indication of implant dose.

[0040] The process chamber 105 of FIG. 2 suffers from a non-uniformitywithin the chamber which negatively impacts process condition uniformitytherein. In particular, the access port 145 for receiving wafers forprocessing includes an OEM slot valve, which is a valve having agenerally rectangular opening which mounts to the box-like access portopening 255 in the process chamber 105. The opening in the slot valvedisturbs the cylindrical shape in an interior peripheral portion of theprocess chamber 105 which may cause non-uniformities in the processconducted therein. For example, in the plasma immersion ion implantationtype chamber 105, the disturbance (non-uniformity) disrupts the plasmadensity uniformity therein, thereby resulting in potential implantationvariations across the wafer.

[0041] The present invention overcomes the disadvantages associated withthe prior art slot valve discussed above by employing an annular ringvalve within the wafer process chamber. An exemplary ring valve andassociated wafer processing system is illustrated in FIGS. 3 and 4a-4 b.In FIG. 3, a wafer processing system 200 includes a process chamber 202,a wafer transfer chamber 204, and a load lock chamber 206, respectively.The process chamber 202 is similar to the chamber 105 of FIG. 2 in manyrespects, however, the rectangular slot valve is replaced with anannular ring valve, designated at reference numeral 210 whichperipherally encircles a generally middle interior portion of theprocess chamber 202.

[0042] The ring valve 210 is operable effectively to open and close theprocess chamber 202 by moving between a first, open position (aretracted position) and a second, closed position (an extendedposition). As illustrated in FIG. 4a, in a first, open position 212, thering valve 210 is in a retracted position and resides within an annularlip of the process chamber 202, thereby opening a chamber access slot214 and placing a chamber interior region 216 in fluid communicationwith the transfer chamber 204. In the open position 212, a wafer mayenter or exit the process chamber 202 in one of many ways. For example,a wafer may enter or exit the process chamber 202 using a multi-axis,multi-jointed articulated transfer arm to transfer a wafer to and fromthe process chamber 202. Alternatively, wafer transfer may beeffectuated using a transfer arm employing a single axis wafer movementto and from the process chamber 202, as will be described in greaterdetail infra.

[0043] The second, closed ring valve position is illustrated in FIG. 4b,designated at reference numeral 217 in which the ring valve 210sealingly engages a top interior portion 218 of the process chamber 202about a periphery thereof. Simultaneously, when in the closed position,a bottom portion of the ring valve engages a portion 225 of the processchamber. Preferably, the ring valve 210 is actuated and thereby movedbetween the open and closed positions via an actuation member 220 whichselectively exerts a force upon a bottom portion 220 of the ring valve210, as may be desired.

[0044] According to one exemplary embodiment of the present invention,the actuation member 220 includes an internally threaded screw/borearrangement in which the rotation of an internal screw member within athreaded bore results in a variation in the vertical position of thering valve 210 within the process chamber 202. Alternatively, forexample, a bellow type fluid actuator may be implemented. Any manner ofactuating or otherwise manipulating the vertical position of the ringvalve 210 may be utilized and any such actuation device or system iscontemplated as falling within the scope of the present invention.

[0045] In the second, closed position 217, as illustrated in FIG. 4b,the ring valve 210 seals or otherwise fluidly isolates the processchamber 202 from the transfer chamber 204. In this manner, the ringvalve 210 prevents the plasma (or other type processing environment) togenerate deposits or otherwise affect the wafer transport systemassociated with the transfer chamber 204. The ring valve 210 generallyis annular in shape and preferably contains a substantially uniforminner peripheral surface 224. Consequently, when in the closed position217, the access port 214 associated with the process chamber 202 iscovered and a substantially uniform periphery exists therein, therebyfacilitating uniform processing conditions within the process chamber202. In particular, with regards to a plasma immersion ion implantationapparatus, the substantially uniform inner peripheral surface 224 of thering valve 210 facilitates a uniform plasma density throughout theprocess chamber 202, thereby providing a more uniform ion implantationacross the surface of the wafer W.

[0046] According to a preferred embodiment of the present invention, thering valve 210 sealingly engages a top interior portion 218 of thechamber 202 in a center portion thereof and thus defines a top portionand a bottom portion of the process chamber, respectively. Preferably,the ring valve 210 is associated with the bottom portion of the processchamber 202 as illustrated in FIGS. 3-4 b; that is, the actuator member220 which manipulates the ring valve 210 is associated with the bottomportion of the process chamber 202. Alternatively, however, the presentinvention contemplates the ring valve 210 being associated with the topprocess chamber portion. For example, in such an embodiment the actuatormember 220 may be attached to the ring valve 210 and operate toeffectively lower a suspended ring valve 210 down from a first, openposition to a second, closed position which sealingly engages a bottominterior portion 225 of the process chamber 202.

[0047] In addition, the ring valve 210 preferably is composed of amaterial which is the same or similar to the process chambercomposition. Thus, the ring valve 210 preferably exhibits a coefficientof thermal expansion which approximates that of the process chamber 202,thus maintaining an effective sealing engagement for the chamber whenthe valve 210 is in the closed position over a plurality of processtemperatures.

[0048] According to another aspect of the present invention, the waferprocessing system 200 of FIG. 3 provides a transfer chamber 204 inconjunction with the load lock chamber 206 and the process chamber 202which improves system operation by reducing process chambercontamination. The contamination improvement is effectuated by providingfor a wafer transport to the process chamber which does not require aprocess chamber pump and vent cycle for each wafer transport as in priorart systems. Therefore the wafer processing system 200 allows theprocess chamber 202 to be maintained at the process environment pressureat all times throughout the wafer transport process. Such feature alsoadvantageously allows wafer processing to commence expediently since theprocess chamber pressure is maintained during wafer transport.

[0049] The system 200 of FIG. 3 includes the load lock chamber 206having a load lock cover 250 which is operable to move between twopositions: a first, closed position in which the load lock cover 250 islowered within a shallow T-shaped recess 252 and sealingly engages andthereby isolates a portion of the load lock chamber 250 (correspondingto the recess 252) from the transport chamber 204, and a second, openposition (as illustrated in FIG. 3) wherein the load lock cover 250 islifted or otherwise moved out of the recess 252 in order to bring therecess portion 252 of the load lock chamber 206 into fluid communicationwith the transfer chamber 204.

[0050] The load lock chamber 206 further includes a load lock coveractuator 254 which is operatively coupled to the load lock cover 250 andoperable to move the load lock cover 250 between the open and closedpositions, respectively. Any actuation mechanism may be utilized and iscontemplated by the present invention. In addition, the load lockchamber 206 includes a plurality of pins 256 operated by a pin assembly258 to position the wafer W vertically into a wafer transfer plane 260.Lastly, the load lock chamber 206 includes a pump (not shown) associatedtherewith which is operable to pump down the recess portion 252 down toa processing pressure (e.g., about 1 millitorr) prior to transferringthe wafer W to the process chamber 202.

[0051] The system 200 operates in the following manner. The load lockcover 250 is initially in a closed position, wherein the cover 250 issealingly engaged with the shallow T-shaped recess 252, via the actuator254. Thus, the recess portion 252 is fluidly isolated from the transferchamber 204. A wafer W is the input into the recess 252 via a sideaccess port 262. Upon closing the port 262, the pump (not shown) pumpsdown the pressure in the recess 252 (i.e., evacuates the recess region)down to the desired process environment pressure. Upon reaching thedesired pressure, the load lock cover 250 is lifted via the actuator254, thereby placing the recess 252 in fluid communication with thetransfer chamber 204.

[0052] Operation continues by actuating the pins 256 via the pinassembly 258, wherein the pins 256 contact a bottom portion of the waferW and lift the wafer into the wafer transfer plane 260. A wafer transferassembly (not shown in FIG. 3) then takes the wafer W from the load lockchamber 206 and transfers the wafer W to the process chamber 202 (afteropening the ring valve 210 associated therewith). Upon the wafer Wentering the process chamber 202 and the wafer transfer assembly exitingthe process chamber 202, the ring valve 210 is moved to the closedposition, thereby fluidly isolating the process chamber interior fromthe transfer chamber 204. Since the transfer chamber 202 has remained atits process pressure throughout this entire process, processing cancommence therein immediately without a pump and vent cycle associatedtherewith, thereby decreasing contamination within the process chamber202 and improving processing throughput.

[0053] The above feature has been described in conjunction with a singleload lock chamber 206, however, the present invention contemplates suchoperation with multiple load lock chambers, preferably two such chambers206. In such a case, while a wafer is being transferred from one loadlock chamber to the processing chamber for processing, the second loadlock chamber concurrently contains a wafer and is pumping down to theprocessing pressure. Consequently, as soon as a wafer is removed fromthe process chamber 202, another is immediately transferred thereto fromthe second load lock chamber, thereby substantially increasing thesystem throughput while minimizing process chamber contamination sincethe pump and vent cycle associated with either load lock chamber doesnot adversely impact a wafer processing and transfer cycle time.

[0054] Another aspect of the present invention relates to a wafertransfer apparatus for transferring a wafer W from a load lock chamberto a process chamber in an efficient, reliable manner. As will becomeevident in the discussion below, the wafer transfer apparatus of thepresent invention reduces the number of moving, frictionally engagablecomponents over prior art systems and thereby reduces particulatecontamination associated therewith. In addition, the design simplicityadvantageously reduces system cost and improves system reliability.

[0055] In order to best understand the various advantageous features ofthe present invention, a brief description of a prior art type wafertransfer apparatus is provided. FIGS. 5 and 6 illustrate perspectiveviews of a multi-axis, multi-jointed articulated wafer transfer arm 300which is capable of movement between an extended position (FIG. 5) and aretracted position (FIG. 6). In addition, FIGS. 7a-7 d illustrate asequence of successive movements between the extended and retractedpositions, respectively. As illustrated in FIGS. 5 and 6, the transferarm 300 can rotate about an axis on a platform 302 to move an endeffector 304 for alignment with openings in the load lock chamber andprocess chambers, respectively.

[0056] The prior art transfer arm 300 includes an elongated base arm 306which is rotatable in a level plane about a base axis 307 a; a forearm308 is rotatably coupled to the base arm 306 at an opposite end about aforearm axis 307 b. The forearm 308 in turn is rotatably coupled to awrist member 310 for rotation about a wrist axis 307 c. As seen in FIGS.5-7 d, the prior art transfer arm 300 includes multiple arm memberswhich rotate about a plurality of axes 307 a-307 c. Although such an arm300 provides for compact movements, the plurality of joints androtational arm members provide the potential for particulatecontamination due to the frictional engagement of such arm membersagainst one another and their movement about the multiple axes. In starkcontrast, the wafer transfer system of the present inventionsubstantially reduces particulate contamination, reduces cost andimproves the system reliability over the prior art by utilizing one ormore elongate transfer arms employing a single axis wafer movementbetween the load lock chamber 206 and the process chamber 202,respectively.

[0057]FIG. 8a is a plan view of a wafer processing system 400, forexample, a system similar to the system 200 of FIG. 3. The system 400includes a system housing 401 which encompasses a process chamber 402, atransfer chamber 404, and a load lock chamber 406. The process chamber404 includes a gas manifold 408 associated therewith for theintroduction of process gases such as a dopant species in the case of aplasma immersion ion implantation system. In addition, the load lockchamber 406 includes an external access port 410 by which a wafer W mayenter the system 400 from an external wafer cassette (not shown).

[0058] Preferably, within the transfer chamber 404 resides a wafertransfer axis 412 about which a single axis wafer movement transfer arm414 rotates. The wafer transfer arm 414 includes an elongate transfermember 416 having generally U-shaped end effectors 418 at each distalend thereof. The transfer arm 414 rotates about the axis 412 at least180° and may rotate a full 360°, as may be desired. In rotating 180°,the transfer arm 414 is operable to move between two substantiallyidentical transfer positions (as illustrated in FIG. 8a), wherein eachof the transfer positions correspond to an end effector 418 within theload lock chamber 406 and the process chamber 402, respectively. As willbe discussed in greater detail below, the transfer positions correspondto method steps in which a wafer W is transferred to or from the processchamber 402 and the load lock chamber 406. In such an instance, theinternal access port between the load lock chamber 406 and the transferchamber 404 is open as well as the access port (e.g., the ring valve 210of FIGS. 3-4 b) between the transfer chamber 404 and the process chamber402. Therefore in the instance illustrated in FIG. 8a, the load lockchamber 406 and the process chamber 402 are in fluid communication withone another via the transfer chamber 404.

[0059] The transfer arm 412 is also operable to rotate 900 into aneutral position, as illustrated in FIG. 8b, wherein the transfer arm412 resides within the transfer chamber 404 entirely. In the neutralposition, the internal access ports for the load lock chamber 406 andthe process chamber 402 typically are closed, for example, wherein awafer W is undergoing processing within the process chamber and anotheralready processed wafer is being removed from the load lock chamber 406,replaced with an unprocessed wafer, and being pumped down to aprocessing environment pressure. Afterwards, when processing in theprocess chamber 402 is complete and the pump and vent cycle in the loadlock chamber 406 is finished, the internal access ports of therespective chambers into the transfer chamber 404 are again opened andthe transfer arm 414 may again rotate 90° into the transfer position,pick up the wafers in the chambers 402 and 406 via the end effectors418, and rotate another 180° to switch the wafers therebetween.

[0060] Note that the transfer arm 414 of the present invention issubstantially more simple than the multi-axis, multi-jointed articulatedtransfer arm 300 of the prior art (FIGS. 5-7 d). Instead, the transferarm 412 is a single, elongate member which provides single axis wafermovement during wafer transfer about the axis 412. Such single axiswafer movement reduces particulate contamination by avoiding multi-axismovements and the frictional engagement of multiple moving membersinherent in such arrangements.

[0061] In the system 400 of FIGS. 8a and 8 b, the housing 401 isgenerally circular to accommodate the generally circular transfermovements of the wafer transfer arm 414. According to an alternativeembodiment of the present invention, for systems requiring a morecompact housing footprint, a system 450 employing a generally ellipticalsystem housing 452 is provided, as illustrated in FIGS. 9a-9 d. In FIGS.9a-9 d, a wafer transfer arm 454 rotates about the axis 412. Thetransfer arm 454 differs slightly from the transfer arm 414 of FIGS. 8aand 8 b in that the arm 454 contains end effectors 456 at each distalend that rotate about an end axis 458 in a controlled manner (i.e., as afunction of the rotational position of the arm 454 about the center axis412). In the above manner, the length or space footprint which thetransfer arm occupies varies as the arm 454 rotates about the axis 412.

[0062]FIGS. 9a-9 d illustrate the transfer arm 454 in four differentrotational positions to illustrate an exemplary manner in which thetransfer system 450 provides a reduced housing footprint. The system 450further includes a controller (not shown) which controls the rotation ofthe end effectors 456 about their respective end axes 458. Preferably,the controller senses a rotational position of the base transfer arm 454about the center axis 412 and uses the sensed rotational position tocontrol the rotation of the end effectors 456 about their end axes 458.As illustrated in FIG. 9a, when the transfer arm 454 is in a generallyhorizontal orientation, the end effectors 456 are rotated to theirextended orientations, while in FIG. 4c, when the transfer arm 454 is ina generally vertical orientation, the end effectors 456 are rotated totheir retracted orientations. Therefore, as illustrated in FIGS. 9a-9 d,the end effectors 456 (and therefore the wafers W) travel between thechambers 402 and 406 in a generally elliptical transfer path.

[0063] The wafer transfer arm of FIGS. 8a-9 d illustrate wafer transfersbetween the process chamber 402 and a single load lock chamber 406.According to another embodiment of the present invention, the wafertransfer system may be employed with multiple load lock chambers(preferably two such chambers) in order to further improve processingthroughput over prior art systems. In some processing operations, theprocessing cycle time is less than the pump and vent cycle timeassociated with establishing a process environment pressure within theload lock chamber. In such an instance, although the processing of awafer in the process chamber is complete, the system must wait for theload lock pressure to equalize the process chamber pressure, resultingin dead time in the process chamber where no wafer processing isoccurring. According to the alternative embodiment of the presentinvention, the process chamber maximizes its processing efficiency bymaintaining processing of wafers therein substantially constantly, withprocessing discontinuing only for the time necessary to swap theprocessed wafer with a new, unprocessed wafer. Using the multiple loadlock chambers generally in parallel with one another allows one loadlock chamber to pump and vent while the other load lock chamber isswapping wafers with the process chamber. Consequently, as soon asprocessing is completed, a load lock chamber is ready to “swap in” a newunprocessed wafer.

[0064] An exemplary system for effectuating the above functionality isshown in FIGS. 10a and 10 b, designated at reference numeral 500. Thesystem 500 includes a system housing 501 which incorporates the processchamber 402 and the transfer chamber 404 in a manner similar to FIGS. 8aand 8 b. The system 500 further includes two load lock chambers 406 aand 406 b having external access ports 410 a and 410 b associatedtherewith. The load lock chambers 406 a and 406 b are operable to pumpand vent a wafer therein down to a process environment temperature andwafers are transferred to and from the process chamber 402 via twosingle axis wafer movement transfer arms 414 which couple to and rotateabout separate axes 512 a and 512 b within the transfer chamber 404. Asillustrated in FIG. 10a, when one transfer arm 512 b resides in atransfer position (i.e.,swapping wafers between chambers 406 b and 402),the other transfer arm 512 a (illustrated in phantom for clarity)resides in a neutral position, thereby allowing the other load lockchamber 406 a to pump down to the process environment pressure.

[0065] Both transfer arms 512 a and 512 b of FIGS. 10a and 10 bpreferably swap wafers W between their respective load lock chamber andthe process chamber 402 within a wafer transfer plane. In order to avoidthe transfer arms 512 a and 512 b from interfering with each other, eacharm 414 is positioned generally within the wafer transfer plane,however, each is positioned at a slightly different vertical position,as may be appreciated.

[0066]FIGS. 10a and 10 b illustrate a system housing 501 which isgenerally circular in shape to accommodate the generally circulartransfer paths of the transfer arms 414 about their respective axes 512a and 512 b. Alternatively, if a smaller system housing footprint isneeded or desired, a system as illustrated in FIGS. 11a-11 d, designatedgenerally at reference numeral 550, is provided. The system 550 has agenerally rectangular system housing 552 including a generally oblongtransfer chamber 554, the process chamber 402 and two load lock chambers406 a and 406 b, respectively. The system 550 operates generally underthe operational principles discussed above in conjunction with FIGS.9a-9 d and FIGS. 10a and 10 b. That is, two transfer arms 560 a and 560b within the transfer chamber 554 operate in conjunction with oneanother to maximize the utilization efficiency of the processingchamber. In addition, each transfer arm 454 a and 454 b are similar tothe transfer arm 454 of FIGS. 9a-9 d and thus traverse a generallyelliptical transfer path.

[0067] The systems 400, 450 of FIGS. 3 and 8a-9 d may be utilized inaccordance with a method of serially transferring wafers to and from aprocess chamber. One exemplary method is illustrated in FIG. 12 anddesignated at reference numeral 600. The method begins at step 602 witha system initialization, wherein the transfer arm 414 is rotated intothe neutral position, the load lock cover 250 associated with the loadlock chamber 206, 406 is actuated into a closed position and the ringvalve 210 associated with the process chamber 202, 402 is closed. Awafer W is then loaded into the recess portion 252 via the access port262, 410 of the load lock chamber 206, 406 at step 604 and the recessportion 252 is then pumped or otherwise evacuated to equalize thepressure between the recess portion 252 of the load lock chamber 206,406 and the transfer chamber 204, 404/process chamber 202, 402 at step606.

[0068] Once the pressure equalization has been obtained, the load lockcover 250 is lifted via the actuator 254 and the ring valve 210 is movedto an open or retracted position 212 via the actuator 220 at step 608,thereby bringing the recess portion 252 of the load lock chamber 206,406 into fluid communication with the process chamber 202, 402. Thewafer W within the load lock chamber 206, 406 is then lifted into thewafer transfer plane 260 via the pin assembly 256 at step 610 and thetransfer arm 414 is rotated from the neutral position of FIG. 8b intothe transfer position of FIG. 8a at step 612. The wafer W is thenlowered onto the end effector 418 of the transfer arm 414 at step 614via the pin assembly 256 and the transfer arm 414 is rotated 1800 tothereby transfer the wafer W from the load lock chamber 206, 406 to theprocess chamber 202, 402 in an efficient, single axis wafer movement atstep 616.

[0069] The method 600 of FIG. 12 continues at step 618 where the pinassembly within the process chamber 202, 402 lifts the wafer W off ofthe transfer arm 414. The transfer arm 414 then rotates 90° into theneutral position as illustrated in FIG. 8b at step 620, followed byclosing the load lock cover 250 and the ring valve 210 at step 622,wherein wafer processing and the transfer of another unprocessed waferinto the load lock chamber recess 252 is initiated at step 624. Themethod 600 then returns to step 606 and the recess portion 252 of theload lock chamber 206, 406 is pumped down to the process environmentpressure and the various method steps are repeated. In this next case, awafer resides in both the load lock chamber 206, 406 and the processchamber 202, 402. Thus at step 610, both wafers are lifted into thewafer transfer plane and both wafers are lowered onto respective ends ofthe transfer arm at step 614. Lastly, step 618 will include theoff-loading of both wafers.

[0070] The method 600 of FIG. 12 advantageously reduces particulatecontamination and increases throughput over prior art systems bymaintaining the process chamber at the process environment pressurethroughout the load process 600. Thus the process chamber 202, 402avoids a pump and vent cycle each time a wafer is transferred thereto.Although the method 600 provides several advantages over prior artsystems, process throughput may be further improved using multiple loadlock chambers such as those illustrated in FIGS. 10a-11 d. A method 700of transferring and processing wafers in a processing system isillustrated in FIGS. 13a-13 c.

[0071] At step 702 of FIG. 13a the system 500, 550 is initialized; thatis both transfer arms 414 are in neutral positions, both load lockcovers 250 are closed and the ring valve 210 is closed. Thus the recessregions 252 within the load lock chambers 406 a and 406 b are fluidlyisolated from the rest of the system. An unprocessed wafer W is theninserted into one of the load lock chambers 410 a via an external accessport at step 704 and the recess portion 252 of the load lock chamber 410a is then pumped down to the process chamber pressure at step 706. Oncepumping is complete at step 708 and processing is complete at 710 (notpresently relevant because no wafer is in the process chamber 202, 402at this time), two different sets of steps 712 and 714 begin to occur inparallel because two load lock chambers exist.

[0072] Step set 712 includes the step of moving the unprocessed wafer Wwithin the load lock chamber 410 a into the wafer transfer plane 260 bylifting the load lock cover 250 and actuating the pin assembly 256 viathe actuator 258 at step 720. The ring valve 210 is then opened at step722 and the transfer arm 414 associated with the first axis 512 a movesthe wafer W from the load lock chamber 410 a to the process chamber 202,402 at steps 724, 726 and 728 (see FIGS. 13a and 13 b). Note thatinitially no wafer is in the process chamber 202, 402, however,subsequently, the wafer transfer of steps 724-728 will include twowafers (i.e., a wafer swap).

[0073] The wafer W is deposited in the process chamber 202, 402 (andlater in both chambers) via the pin assembly therein at step 730. Thetransfer arm 414 associated with the axis 512 a is then rotated into theneutral position at step 732. Once in the neutral position, the transferarm 414 associated with the axis 512 a will not interfere with the loadlock chamber 406 a. The load lock cover 250 for the load lock chamber406 a and the ring valve 210 of the process chamber 202, 402 are thenclosed at step 734. At this time no processed wafer was swapped so nowafer removal occurs at the first load lock chamber 406 a at step 736,however, later in the process 700 such a swap will occur.

[0074] In parallel with the step set 712 is another set of steps 714associated with the second load lock chamber 406 b. While the first loadlock chamber 406 a is swapping its wafer with the process chamber 202,402, another unprocessed wafer W is inserted into the second load lockchamber 406 b via the external access port 410 b at step 750. Theexternal port 410 b is closed and the chamber 406 b is then pumped downat step 752. Once the pumping is complete at step 754 and the processingis complete at step 756 (corresponding to the wafer transferredinitially from the first load lock chamber 406 a), the wafer W in thesecond load lock chamber 406 b is moved into the wafer transfer plane280 at step 758 (FIG. 13c) when the cover 250 is lifted via the actuator254 at step 760 and the transfer arm 414 associated with second axis 512b swaps the unprocessed wafer from the second load lock chamber 406 bwith the processed wafer via steps 762-768. The transfer arm 414associated with the second axis 512 b is then moved to the neutralposition at step 770, the doors close at step 772 and processingcommences.

[0075] Note that although the first unprocessed wafer W entered theprocess chamber 202, 402 via the first load lock chamber 406 a and thetransfer arm 414 associated with the first axis 512 a, the wafer, uponbeing processed, exits the process chamber 202, 402 and gets transferredto the second load lock chamber 406 b via the transfer arm 414associated with the second axis 512 b. Therefore according to theexemplary method 700 of the present invention, wafers enter and exitfrom different load lock chambers. Thus, once the ring valve 210 isclosed at step 772 of FIG. 13c, the unprocessed wafer W from the secondload lock chamber 406 b will be processed and the processed wafer willbe removed from the second load lock chamber at step 774. The method 700then continues at step 750.

[0076] As can be seen from the above, the method 700 of the presentinvention enhances the utilization efficiency of the process chamber202, 402 by immediately swapping a new unprocessed wafer therein as soonas wafer processing is complete. Because both load lock chambers 406 a,406 b work generally in parallel, while one is swapping wafers with theprocess chamber 202, 402 the other is getting a new unprocessed waferand initiating a pump and vent cycle without impacting the processenvironment in the process chamber.

[0077] Although the invention has been shown and described with respectto a certain preferred embodiment or embodiments, it is obvious thatequivalent alterations and modifications will occur to others skilled inthe art upon the reading and understanding of this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described components (assemblies, devices,circuits, etc.), the terms (including a reference to a “means”) used todescribe such components are intended to correspond, unless otherwiseindicated, to any component which performs the specified function of thedescribed component (i.e., that is functionally equivalent), even thoughnot structurally equivalent to the disclosed structure which performsthe function in the herein illustrated exemplary embodiments of theinvention. In addition, while a particular feature of the invention mayhave been disclosed with respect to only one of several embodiments,such feature may be combined with one or more other features of theother embodiments as may be desired and advantageous for any given orparticular application.

What is claimed is:
 1. A wafer handling system for a wafer processingapparatus, comprising: at least one wafer load lock chamber; a waferprocessing chamber; a transfer chamber operatively coupled to the waferload lock chamber and the wafer processing chamber, the transfer chamberincluding a wafer transfer mechanism comprising a transfer arm pivotablycoupled to a portion of the transfer chamber forming an axis, whereinthe transfer arm is operable to rotate about the axis to transfer awafer between the wafer load lock chamber and the process chamber in asingle axis wafer movement.
 2. The system of claim 1, wherein thetransfer arm comprises an elongate member having an end effector on atleast one generally distal end thereof, wherein the end effectorinterfaces with the wafer to effectuate the wafer transfer between theload lock chamber and the process chamber.
 3. The system of claim 2,wherein the end effector is a generally U-shaped member.
 4. The systemof claim 2, wherein the elongate member is coupled to the axis at amidpoint thereof, and wherein the elongate member has an end effector oneach generally distal end such that when the transfer arm is in atransfer position, one end effector is within the load lock chamber andthe other end effector is within the process chamber.
 5. The system ofclaim 1, wherein the transfer arm is operable to rotate between aplurality of positions, wherein in a first position the transfer arm iswithin at least one of the load lock chamber and the process chamber andin a second position the transfer arm is within the transfer chamber. 6.The system of claim 1, wherein the wafer processing chamber comprises aplasma immersion ion implantation apparatus.
 7. The system of claim 1,further comprising an end effector coupled to the transfer arm at agenerally distal end of thereof and defining an end axis thereat, andwherein the end effector is rotatably coupled to the generally distalend of the transfer arm for rotational movement about the end axis. 8.The system of claim 7, further comprising a controller associated withthe system for sensing a rotational position of the transfer arm andcontrolling a rotational movement of the end effector about the end axisas a function of the rotational position, thereby effectuating agenerally elliptical end effector transfer path when transferring thewafer between the load lock chamber and the process chamber.
 9. Thesystem of claim 1, wherein the wafer load lock chamber further comprisesa load lock cover operable to move between two positions, wherein afirst position fluidly isolates a portion of the wafer load lock chamberfrom the transport chamber, thereby allowing a pressure in the portionof the wafer load lock chamber to differ from a pressure in thetransport chamber during a wafer transfer from an ambient pressureenvironment external the wafer load lock chamber to the isolated portionof the wafer load lock chamber, and wherein a second position of theload lock cover brings the portion of the wafer load lock chamber intofluid communication with the transport chamber for transfer of a waferbetween the wafer load lock chamber and the processing chamber via thetransfer arm.
 10. The system of claim 9, further comprising a pumpassociated with the portion of the wafer load lock chamber, wherein thepump is operable to reduce a pressure within the portion of the waferload lock chamber when the load lock cover is in the first position,thereby substantially matching a pressure in the portion of the waferload lock chamber with a pressure in the transfer chamber and theprocessing chamber.
 11. The system of claim 1, wherein the wafer loadlock chamber further comprises: an external access port for receiving awafer into the wafer load lock chamber; and a selectively positionableisolation member within the wafer load lock chamber, positionablebetween an isolation position and a non-isolation position, wherein inthe isolation position the isolation member sealingly engages a portionof the wafer load lock chamber associated with the external wafer loadlock chamber access port, thereby permitting the transfer of a wafer toor from the wafer load lock chamber from an external ambient environmentvia the wafer load lock chamber access port without impacting processingconditions within the transfer chamber and the processing chamber, andwherein when the isolation member is in the non-isolation position theportion of the wafer load lock chamber is in fluid communication withthe transfer chamber.
 12. The system of claim 11, further comprising anactuator operatively coupled to the isolation member, wherein theactuator is operable to selectively position the isolation member in theisolation position and the non-isolation position, respectively.
 13. Thesystem of claim 1, further comprising another wafer load lock chamberoperatively coupled to the transfer chamber.
 14. The system of claim 13,wherein the transfer chamber further comprises another transfer armpivotably coupled to a portion of the transfer chamber forming anotheraxis, and wherein the another transfer arm is operable to rotate aboutthe another axis to transfer a wafer between the another wafer load lockchamber and the process chamber in a single axis wafer movement.
 15. Thesystem of claim 14, wherein axes of the transfer arm and the anothertransfer arm are different.
 16. The system of claim 15, furthercomprising load lock covers associated with the wafer load lockchambers, respectively, wherein each load lock cover is operable to movebetween two positions, wherein a first position fluidly isolates aportion of the respective wafer load lock chamber from the transportchamber, thereby allowing a pressure in the portion of the wafer loadlock chamber to differ from a pressure in the transport chamber during awafer transfer from an ambient pressure environment external therespective wafer load lock chamber to the isolated portion of the waferload lock chamber, and wherein a second position of the load lock coverbrings the portion of the respective wafer load lock chamber into fluidcommunication with the transport chamber for transfer of a wafer betweenthe respective load lock chamber and the processing chamber via therespective transfer arm.
 17. The system of claim 15, wherein the eachwafer load lock chamber further comprises: an external access port forreceiving a wafer into the wafer load lock chamber; and a selectivelypositionable isolation member within the wafer load lock chamber,positionable between an isolation position and a non-isolation position,wherein in the isolation position the isolation member sealingly engagesa portion of the wafer load lock chamber associated with the externalload lock chamber access port, thereby permitting the transfer of awafer to or from the wafer load lock chamber from an external ambientenvironment via the load lock chamber access port without impactingprocessing conditions within the transfer chamber and the processingchamber, and wherein when the isolation member is in the non-isolationposition the portion of the wafer load lock chamber is in fluidcommunication with the transfer chamber.
 18. A method of transferring awafer to a wafer processing apparatus, comprising the steps of: loadinga wafer into a wafer load lock chamber; rotating a transfer arm into thewafer load lock chamber to retrieve the wafer therein; and rotating thetransfer arm out of the wafer load lock chamber and into a processchamber to deposit the wafer therein, wherein the rotating of thetransfer arm occurs in a single axis wafer movement.
 19. The method ofclaim 18, further comprising the steps of: sealing a portion of thewafer load lock chamber from the process chamber before loading thewafer into the wafer load lock chamber; and evacuating the sealedportion of the wafer load lock chamber, thereby substantially equalizinga pressure therein with a pressure in the process chamber.
 20. Themethod of claim 19, further comprising the steps of: unsealing theportion of the wafer load lock chamber after the sealed portion has beenevacuated; and adjusting a vertical position of the wafer to place thewafer in a wafer transfer plane before rotating the wafer transfer arminto the wafer load lock chamber.
 21. The method of claim 20, furthercomprising opening the process chamber before rotating the transfer arm.22. The method of claim 18, wherein the transfer arm comprises anelongate member having a rotational axis generally at its midpoint andend effectors at each generally distal end, and wherein rotating thetransfer arm into the wafer load lock chamber and rotating the transferarm into the process chamber occurs in the same step, wherein eachrespective end effector moves between the wafer load lock chamber andthe process chamber, respectively.
 23. A method of transferring a waferto a wafer processing apparatus, comprising the steps of: (a) fluidlyisolating a portion of a wafer load lock chamber from a transfer chamberand a process chamber, respectively; (b) loading a wafer into theisolated portion of the wafer load lock chamber from an external source;(c) evacuating the portion of the wafer load lock chamber until apressure therein substantially matches a pressure in the processchamber; (d) establishing fluid communication between the portion of thewafer load lock chamber and the process chamber via the transferchamber; (e) rotating a transfer arm into a transfer position, whereinthe transfer arm comprises an elongate member with end effectors at eachgenerally distal end with a rotational axis at about is midpoint,wherein the transfer position comprises one end effector being locatedwithin the wafer load lock chamber and the other end effector beinglocated within the process chamber; (f) retrieving the wafer from theload lock chamber and a wafer from the process chamber, if any, usingthe end effectors; (g) rotating the transfer arm so that the endeffector which previously was located within the wafer load lock chamberis now in the process chamber and the end effector which previously waslocated in the process chamber is now in the wafer load lock chamber,wherein the rotation of the transfer arm comprises a single axismovement; (h) depositing the wafer in the process chamber and the wafer,if any, in the wafer load lock chamber; (i) rotating the transfer arminto a neutral position, wherein both end effectors are located in thetransfer chamber; (j) fluidly isolating the portion of the wafer loadlock chamber; (k) processing the wafer in the process chamber; (l)removing the wafer from the isolated portion of the wafer load lockchamber substantially while the wafer is being processed in the processchamber; and (m) repeating the steps of (b) through (I) until alldesired wafers are processed.
 24. A method of transferring wafers to andfrom a wafer process chamber, comprising the steps of: inserting a firstwafer into a first load lock chamber; equalizing a pressure between thefirst load lock chamber and a process chamber; transferring the firstwafer from the first load lock chamber to the process chamber via afirst transfer arm by rotating the first transfer arm in a single axiswafer movement; processing the first wafer in the process chamber; andtransferring the first wafer from the process chamber to a second loadlock chamber via a second transfer arm by rotating the second transferarm in a single axis wafer movement.
 25. The method of claim 24, furthercomprising the steps of: inserting a second wafer into the second loadlock chamber; equalizing a pressure between the second load lock chamberand the process chamber while the first wafer is being processing in theprocess chamber; and transferring the second wafer from the second loadlock chamber to the process chamber via the second transfer arm when thefirst wafer is being transferred from the process chamber to the secondload lock chamber.
 26. The method of claim 25, further comprising thesteps of: inserting a third wafer into the first load lock chamber;equalizing a pressure between the first load lock chamber and theprocess chamber while the second wafer is being processing in theprocess chamber; and transferring the third wafer from the first loadlock chamber to the process chamber via the first transfer arm when thesecond wafer is being transferred from the process chamber to the firstload lock chamber.